Much of your decision rests upon why you want to enter the world of e-cigarettes. For me, I chose to use them in a non-supported fashion; a way to help me quit smoking tobacco cigarettes. You can read these forums all you want, but you will not truly understand all the chatter until you own an e-cig.
I chose to purchase a penstyle device for the larger battery and cartridge capacity. I soon learned that it is definitely less expensive to refill your spent cartridges rather than purchase new ones from your vendor(s). It is much like the analogy of the drug company that sells the diabetes meter for so cheap since they make their money on the test strip. You will also quickly learn that batteries and cartridges do not last nearly as long as most vendors advertise meaning you have to have smoking
juice, on hond to refill/top off cartridges and exta batteries if you are on the go alot.
Up front cost can be rather high, but once you settle into a routine, costs will begin to balance out as you buy less and less analog cigarettes. One last situation you need to be aware of is the shortages of smoking
juice and device components. Since the vast majority of products are manufactured in China, there are customs issues, quality control issues and high demand from other users that could leave you short of necessary supplies when you need them the most.
I am a new person to this world. I'm in day two without an analog cigarette. Early returns are good, thus far, for me. I have stocked up on extra atomizers and plan to re-order smoke juice next week. Those are the two most important items for which you want to have as extra. A USB pass-through device is, to me, is the second most important accessory if you spend any time at a computer. You PC can supply poer to your e-cig instead of burning up precious battery power.